import java.util.Scanner;

public class Main {

public static void main(String[] args) {

inputStr();

inputInteger();

inputIntInLine();

}

//每行输入一个数值，输入多个数值

public static void inputInteger() {

Scanner scanner = new Scanner(System.in);

String nextLine = scanner.nextLine();

int sum = 0;

while (nextLine != null && !nextLine.equals("")) {

sum += Integer.parseInt(nextLine);

System.out.println(sum);

nextLine = scanner.nextLine();

}

System.out.println("end of input integer");

}

// 每行输入一个字符串，输入多个字符串

public static void inputStr() {

Scanner scanner = new Scanner(System.in);

String nextLine = scanner.nextLine();

while (nextLine != null && !nextLine.equals("")) {

System.out.println(nextLine);

nextLine = scanner.nextLine();

}

System.out.println("end of input string");

}

//输入多个数值，用空格隔开

public static void inputIntInLine() {

Scanner scanner = new Scanner(System.in);

String str = scanner.nextLine();

String[] numstr = str.split(" ");

int[] nums = new int[numstr.length];

for(int i = 0; i < numstr.length; i ++) {

nums[i] = Integer.parseInt(numstr[i]);

}

for(int n: nums) {

System.out.println(n);

}

System.out.println("end of input int in a line");

}

}

做算法题目时用的输入

以下方法在做算法题目时能够正确的结束输入。

import java.util.Scanner;

public class Main{

public static void main(String[] args){

Scanner sc = new Scanner(System.in);

//while(sc.hasNextLine()){

while(sc.hasNext()){

String str = sc.nextLine();

System.out.println(str);

}

sc.close();

}

}

I'm trying to take multi-line user input in Java and split the lines into an array, I need this to solve a problem for an online judge. I'm using a Scanner to take input. I cant determine the end of input. I always get an infinite loop, since I don't know the size of input (i.e number of lines)

Terminating input with an empty String (clicking enter) is still an infinite loop. Code provided below.

public static void main(String[] args) {

ArrayList in = new ArrayList();

Scanner s = new Scanner(System.in);

while (s.hasNextLine() == true){

in.add(s.nextLine());

//infinite loop

}

}

I'm not even sure why the loop executes the first time. I believe the hasNextLine() should be false the first time ,since no input was taken yet. Any help or clarification appreciated.

解决方案

You could use the empty line as a loop-breaker:

while (s.hasNextLine()){ //no need for "== true"

String read = s.nextLine();

if(read == null || read.isEmpty()){ //if the line is empty

break; //exit the loop

}

in.add(read);

[...]

}

这篇博文是用Windows Live Writer写的，看看效果

下面是以前写的程序：java中从控制台输入多行数据 按回车键输入空行结束

//试过几个插件，发现插入代码后都不能复制，

但是插入图片还是很方便的，

用wlw写博客好处是可以离线，

以后就用wlw写，然后发布草稿，再到CSDN插入代码后发表文章，只是写个博客要这么艰难吗！！！

Scanner scanner = new Scanner(System.in);

ArrayList ns = new ArrayList<>();

do {

String string = scanner.nextLine();

if (string.equals("")) {

break;

}

ns.add(Integer.valueOf(string));

} while (true);

System.out.println(ns);

输入：

4

5

6

7

输出：

[4, 5, 6, 7]

插入一个图片试试：

插入一个链接试试：